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排序方式: 共有1021条查询结果,搜索用时 15 毫秒
941.
Omer Gokcumen Qihui Zhu Lubbertus C. F. Mulder Rebecca C. Iskow Christian Austermann Christopher D. Scharer Towfique Raj Jeremy M. Boss Shamil Sunyaev Alkes Price Barbara Stranger Viviana Simon Charles Lee 《PLoS genetics》2013,9(4)
Ancient population structure shaping contemporary genetic variation has been recently appreciated and has important implications regarding our understanding of the structure of modern human genomes. We identified a ∼36-kb DNA segment in the human genome that displays an ancient substructure. The variation at this locus exists primarily as two highly divergent haplogroups. One of these haplogroups (the NE1 haplogroup) aligns with the Neandertal haplotype and contains a 4.6-kb deletion polymorphism in perfect linkage disequilibrium with 12 single nucleotide polymorphisms (SNPs) across diverse populations. The other haplogroup, which does not contain the 4.6-kb deletion, aligns with the chimpanzee haplotype and is likely ancestral. Africans have higher overall pairwise differences with the Neandertal haplotype than Eurasians do for this NE1 locus (p<10−15). Moreover, the nucleotide diversity at this locus is higher in Eurasians than in Africans. These results mimic signatures of recent Neandertal admixture contributing to this locus. However, an in-depth assessment of the variation in this region across multiple populations reveals that African NE1 haplotypes, albeit rare, harbor more sequence variation than NE1 haplotypes found in Europeans, indicating an ancient African origin of this haplogroup and refuting recent Neandertal admixture. Population genetic analyses of the SNPs within each of these haplogroups, along with genome-wide comparisons revealed significant FST (p = 0.00003) and positive Tajima''s D (p = 0.00285) statistics, pointing to non-neutral evolution of this locus. The NE1 locus harbors no protein-coding genes, but contains transcribed sequences as well as sequences with putative regulatory function based on bioinformatic predictions and in vitro experiments. We postulate that the variation observed at this locus predates Human–Neandertal divergence and is evolving under balancing selection, especially among European populations. 相似文献
942.
943.
John S. Tregoning Viviana Buffa Anna Oszmiana Katja Klein Adam A. Walters Robin J. Shattock 《PloS one》2013,8(11)
One potential strategy for the prevention of HIV infection is to induce virus specific mucosal antibody that can act as an immune barrier to prevent transmission. The mucosal application of chemokines after immunisation, termed “prime-pull”, has been shown to recruit T cells to mucosal sites. We wished to determine whether this strategy could be used to increase B cells and antibody in the vaginal mucosa following immunisation with an HIV antigen. BALB/c mice were immunised intranasally with trimeric gp140 prior to vaginal application of the chemokine CCL28 or the synthetic TLR4 ligand MPLA, without antigen six days later. There was no increase in vaginal IgA, IgG or B cells following the application of CCL28, however vaginal application of MPLA led to a significant boost in antigen specific vaginal IgA. Follow up studies to investigate the effect of the timing of the “pull” stimulation demonstrated that when given 14 days after the initial immunisation MPLA significantly increased systemic antibody responses. We speculate that this may be due to residual inflammation prior to re-immunisation. Overall we conclude that in contrast to the previously observed effect on T cells, the use of “prime-pull” has only a modest effect on B cells and antibody. 相似文献
944.
Domenico Otranto Filipe Dantas-Torres Donato de Caprariis Giancarlo Di Paola Viviana D. Tarallo Maria S. Latrofa Riccardo P. Lia Giada Annoscia Edward B. Breitshwerdt Cinzia Cantacessi Gioia Capelli Dorothee Stanneck 《PloS one》2013,8(2)
Background
Dogs are the main reservoir hosts of Leishmania infantum, the agent of human zoonotic visceral leishmaniosis. This study investigated the efficacy of a polymer matrix collar containing a combination of 10% imidacloprid and 4.5% flumethrin as a novel prophylactic measure to prevent L. infantum infections in young dogs from a hyper-endemic area of southern Italy, with a view towards enhancing current control strategies against both human and canine leishmaniosis.Methodology/Principal Findings
The study was carried out on 124 young dogs, of which 63 were collared (Group A) while 61 were left untreated (Group B), from March-April 2011 until March 2012. Blood and skin samples were collected at baseline (April 2011) and at the first, second, third and fourth follow-up time points (July, September 2011 and November 2011, and March 2012, respectively). Bone marrow and conjunctiva were sampled at baseline and at the fourth follow-up. Serological, cytological and molecular tests were performed to detect the presence of L. infantum in the different tissues collected. At the end of the trial, no dog from Group A proved positive for L. infantum at any follow-up, whereas 22 dogs from Group B were infected (incidence density rate = 45.1%); therefore, the combination of 10% imidacloprid and 4.5% flumethrin was 100% efficacious for the prevention of L. infantum infection in young dogs prior to their first exposure to the parasite in a hyper-endemic area for CanL.Conclusions
The use of collars containing 10% imidacloprid and 4.5% flumethrin conferred long-term protection against infection by L. infantum to dogs located in a hyper-endemic area, thus representing a reliable and sustainable strategy to decrease the frequency and spread of this disease among the canine population which will ultimately result in the reduction of associated risks to human health. 相似文献945.
Cardoso E Persi G González N Tumilasci O Arregger A Burgos M Rodríguez V Molina A Contreras LN 《Steroids》2007,72(4):328-334
OBJECTIVE: Adrenal insufficiency has been reported among critically ill HIV-infected patients. This is the first study that attempts to detect subclinical hypoadrenal states in non-critical HIV patients through salivary steroids in response to intramuscular low-dose ACTH injection. PATIENTS AND METHODS: We studied 21 ambulatory adult HIV-infected patients without specific clinical signs or symptoms of adrenal insufficiency. Normal salivary flow-rate and salivary alpha-amylase activity confirmed adequate salivary gland function. Salivary cortisol (SAF) and salivary aldosterone (SAL) were obtained at baseline and 30 min after the injection of 25 microg of ACTH in the deltoid muscle (LDT(s)). Assessment of salivary steroids after stimulation with 250 microg of intramuscular ACTH (HDT(s)) was performed on those who hyporesponded to LDT(s). Basal blood samples were drawn for steroids, renin and ACTH measurements. RESULTS: At baseline SAF and SAL correlated significantly (p=0.0001) with basal serum cortisol and aldosterone (r=0.70 and 0.91, respectively). Plasma ACTH and renin concentrations were within the normal range in all patients. Eight of the twenty-one HIV(+) patients were LDT(s) hyporesponders in either SAF (n:1) or SAL (n:7). LDT(s) repeated in six cases after a year reconfirmed the impairment of aldosterone secretion. LDT(s) hyporesponders had normal steroid responses to HDT(s). CONCLUSIONS: LDT(s) is a simple, safe, well-accepted and non-invasive approach to assess adrenal function in HIV-infected ambulatory patients. It revealed subnormal cortisol (5%) and aldosterone responses (33%) when HDT(s) results were normal. 相似文献
946.
947.
Many tumors produce factors that affect cell-cycle and cell proliferation. In the present study we have analyzed the effect
of a mammary-tumor extract injection on the mitotic activity of several organs in young male C3H/S mice previously standardized
for circadian periodicity. One-half of the animals received an intraperitoneal EA21b tumor extract dose at 16:00 h, while
the other half received saline. Animals were sacrificed on the following day at 08:00, 12:00 or 16:00 h. 4 h after receiving
an injection of colchicine by the same route. Samples of duodenum, kidney, liver, and submaxillary gland were excised and
processed for hematoxylin-eosin staining. Mitotic indices, expressed as the number of colchicine-arrested metaphases per 1,000
nuclei, were assessed in convoluted tubule epithelium, duodenal crypt enterocytes, hepatocytes and submaxillary gland ductal
and acinar sialocytes. All values were expressed as mean ± SEM. Statistical analyses were performed by ANOVA, Bonferroni and
Student’s t-tests. In contrast to the mitotic indices reductions observed in renal convoluted tubules cells and duodenal crypt
enterocytes, neither the submaxillary gland nor the liver were found to contain cell types whose mitotic activity was affected
by the tumor extract. We conclude that EA21b mammary carcinoma contains one or more factors that inhibit the proliferation
of selected populations of normal cells. 相似文献
948.
In Argentina, most information on hepatitis C virus (HCV) genotype distribution comes from studies carried out in Buenos Aires (east province). In order to identify HCV subtypes in central Argentina, nucleotide sequencing of core region was performed in samples from 36 patients living in Córdoba, the second most populated province of Argentina. The sequence analysis identified subtype 2c as the most prevalent (50%), followed by subtype 1b (33%) and to a lesser extent by subtypes 1a (11%), 3a (3%) and 4a (3%). This is the first report of circulation of HCV subtype 2c in this region of Argentina and also such high prevalence has never been found before in the genotype distribution of South America. 相似文献
949.